Iontophoresis electrodes

Safety is an important factor when determining the quality of any iontophoresis electrode. During transdermal iontophoretic delivery using metal electrodes, an applied DC current will induce pH changes on the electrode/skin interface [178], pH measurement is used to eliminate the possibility of unsafe pH changes (chemical bums). It has been reported that the pH shift caused by platinum electrodes has a significant influence on the permeation and stability of insulin [175],... 

Haida, Haruka, Shizuka Ando, Saori Ogami, Ryo Wakita, Hikaru Kohase, Norio Saito, Tomohiko Yoshioka et al. In vitro evaluation of calcium alginate gels as matrix for iontophoresis electrodes. Journal of Medical Dental Sciences 59, no. 1 (2012), 9-16. 

O. Pillai, N. Kumar, C.S. Dey, S. Borkute, S. Nagalingam, and R. Panchagnula, Transdermal iontophoresis of insulin. Part 1 A study on the issues associated with the use of platinum electrodes on rat skin. J. Pharmacy Pharmacol. 55, 1505-1513 (2003). 

Ionic transport occurs in both directions across the skin. For example, to preserve electroneutrality at the anode, cations migrate into the body and anions migrate from the body into the electrode chamber. Hence, iontophoresis can be used for both drug delivery and noninvasive sampling [6,7,17],... 

Santi, P., and R.H. Guy. 1996. Reverse iontophoresis—Parameters determining electroosmotic flow II. Electrode chamber formulation. J Control Release 42 29. 

Srinivasan, V., W.I. Higuchi, and M.H. Su. 1989. Baseline studies with four electrode system The effect of skin permeability increase and water transport on the flux of a model uncharged solute during iontophoresis. J Control Release 10 157. 

Current was delivered to the membranes through silver/silver chloride (Ag/AgCl) electrodes for iontophoresis, whereas stainless steel electrodes were employed for electroporation studies. Of the two model compounds, L-glutamic acid carries a net negative charge of 1 at pH 7.4, whereas estradiol is nonionized. Hence, they were delivered under the cathode and anode, respectively. 

Electrolysis at the electrodes needs to be minimized, since this will alter electrolyte composition. Partly for this reason, impedance measurements should be made at current densities on the order of 1 xA/cm or less [17]. Making impedance measurements at 1 pA/cm or less has the added advantage of minimizing iontophoresis and electroosmosis, which can decrease the skin s impedance with time [16,17]. 

In addition to solute structure, a number of factors affecting iontophoretic transport need to be gained for the development of useful optimal iontophoretic drug delivery systems. These include the behavior of solute ions in solution during iontophoresis, mechanisms of solute ion transport through the skin, the effect of different power sources, the choice of electrodes, the composition of vehicles, and the influence of other ions present in the process of drug delivery. 

Iontophoresis of mepivacaine and lidocaine with epinephrine have been reported in human cadaver bladders and in clinical trials by Lugnani et al. [41], The study reported that the active electrode must be sited close to the geometric center of the bladder cavity in order to anesthesize the entire bladder. Siting the electrode close to the wall resulted in anesthesia of only that section of the bladder. 

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